Measurements  of $\mathrm{e}^+\mathrm{e}^-$ production with pion beams in HADES have been planned since the end of 90's,  when a secondary  pion beam was constructed at GSI. The main motivation is to learn about dielectron decays of baryon resonances directly excited in pion-nucleon reactions and particularly to verify an important role of vector mesons  in such transitions, predicted by Vector Meson Dominance. This phenomenon is an essential ingredient for a modelling of in-medium spectral function of the $\rho$ meson and, as recently  shown, a successful description of low-mass dilepton production in heavy ion collisions in a broad energy range.